This application incorporates by reference, and claims priority to and the benefit of, German patent application Ser. No. 29903764.9, which was filed on Mar. 2, 1999.
1. Technical Field
The invention relates to a shoe, in particular to a sports shoe with a sole ensemble including a stability element for the selective support of single parts of the sole ensemble.
2. Background Information
The processes in the human foot during walking or running are enormously complex. Between the first contact of the heel and push-off with the toes, a number of different movements take place throughout the entire foot. During these movements, various parts of the foot move or turn with respect to each other.
It is an objective in the construction of sport shoes to obstruct as little as possible these natural movements, such as they occur in barefoot running, and to support the foot only where it is necessary for the intended use of the shoe.
In this context, it has been realized that the conventional homogenous outsole extending over the entire lower area of the shoe does not meet the above mentioned requirements. In particular, the selective support of single parts of the foot is impossible with a homogeneously formed, continuous outsole or a homogenous sole ensemble.
One objective of selective support in shoes is to avoid excessive pronation or supination of the foot, i.e., the turning of the foot to the medial (inner) or the lateral (outer) side by several degrees. The yielding of a sole consisting of foam materials typically causes this turning movement of the foot. The consequences of pronation or supination are premature fatigue of the joints of the foot and/or the knee and/or injury.
One example of a known stability element to avoid pronation or supination is disclosed in German patent number DE 19 904 744. The patent discloses separate stability elements made out of harder materials selectively integrated into a sole or sole ensemble. The stability elements avoid excessive compression of the heavily loaded parts of the sole. It has been found however, that the hardness of the material of such a stability element, as necessary for noticeable pronation or supination control of the foot, significantly reduces the flexibility of the sole which is needed during the push-off phase.
Another method of avoiding pronation or supination is disclosed in U.S. Pat. No. 4,642,911. This patent discloses local modification of the density, and thereby the hardness, of the materials used in the sole in order to locally influence the compression behavior of the sole. The sole disclosed in this patent makes high demands on production technology and thereby leads to excessive costs for a mass-produced sports shoe.
U.S. Pat. No. 4,638,576 discloses a combination of the two approaches. The patent discloses a midsole produced of two different materials to selectively support the foot and at the same time allow flexibility. Additionally, a heel cover is arranged in the rearfoot portion on top of the sole ensemble that is to support, via an additional damping element, the heel from below and three sides. Apart from the high production costs of this construction, the effective support and guidance of the foot is limited by the comparatively soft sole layers below the heel cover. Further, since the supporting effect of the heel cover is limited to the rear foot area, pronation or supination during the movement subsequent to the first contact with the heel cannot be avoided.
In addition to avoiding the above-mentioned pronation or supination, it is an objective of the stability element of the present invention to selectively support the foot to provide smooth movement of the foot during a step, from the first contact of the heel until the final push-off with the toes. Abrupt changes of the phases of the movement are to be avoided to reduce the risk of injuries and/or premature fatigue of the foot and/or knee joints.
It is therefore an object of the present invention to provide a cost-effective manufacturable shoe having, in desired areas of the sole, an improved compression stability to avoid pronation or supination without the above mentioned disadvantages of known stability elements.
It is a further object of the present invention that the shoe should be capable of providing smooth movement during a step, from the first contact with the ground to the final push-off and to provide thereby a complete system for the selective support of the foot.
The present invention relates to an article of footwear, in particular a sports shoe, with a sole ensemble and a stability element for the selective support of single parts of the sole ensemble. The stability element includes a base element extending from a rearfoot portion to a forefoot portion of a shoe along the medial or the lateral side of the forefoot portion of the shoe, and includes at least one support element that extends sideways from the base element and encompasses the sole ensemble on the lateral or the medial side. The at least one support element encompasses the sole ensemble upwardly or downwardly or both. Further, the stability element may include a heel support connected to the base element that encompasses the heel portion of the shoe. The sole ensemble of the shoe is not only supported on the medial and/or lateral side of the forefoot portion, but is also enclosed in a xe2x80x9cframe-likexe2x80x9d manner. Additionally, the shoe may include a second base element for additional lateral support of the shoe.
In one aspect, the invention relates to an article of footwear including a rearfoot portion, a forefoot portion, and a sole ensemble with a stability element. The stability element includes a base element that extends from the rearfoot portion to the forefoot portion. The base element can extend substantially along the medial side of the shoe, or substantially along the lateral side. The base element can include material properties for reducing pronation or supination of a wearer""s foot. The stability element further includes at least one support element. The at least one support element extends sideways from the base element and encompasses the sole ensemble on the medial or lateral side. The at least one support element prevents the sole material from expanding to the side under high pressure on the medial and/or lateral side of the forefoot portion. Since the material cannot expand to the side, this restriction or limitation leads to improved resistance of the sole against compression in the area of the forefoot, which is relevant for the control of pronation and supination, effectively avoiding the turning of the foot to the medial or lateral side. The improvement of the compression stability is further increased by the base element itself, which extends in this area of the sole and which can be made of a harder material than the surrounding sole material.
In another aspect, the stability element includes a heel support connected to the base element. The heel support at least partially encompasses the heel portion of the shoe. In one embodiment, the heel support fully encompasses the heel portion. The heel support ensures that the stability element controls the elasticity and thereby the behavior of the shoe from the first contact with the ground on. At the same time, the connection of the heel support to the base element allows a smooth transition of the foot from the landing phase to the push-off phase, since the effect of the stability element does not only start with the first ground contact of the base element as with known stability elements, but with the first ground contact of the heel support.
In one embodiment, the connection between the base element and the heel support has torsional flexibility to allow a turning movement of the base element with respect to the heel support. A stability element according to the invention therefore allows the natural torsional movements of the forefoot portion with respect to the rearfoot portion. In another embodiment, the heel support is formed as a heel shell, including an inner portion that is inserted into the sole and an external portion that is visible from outside the sole.
In yet another aspect, the stability element includes a second base element extending on the opposite side of the forefoot portion with respect to the first base element. The second base element includes additional support elements extending sideways from the second base element and encompassing the sole ensemble on the side opposite the first base element.
In various embodiments of the above-described stability elements, the support element(s) may encompass the sole ensemble by extending upwardly, downwardly, or both over the sole ensemble. For the additional support of certain portions of the foot, the support element(s) may further encompass not only the sole ensemble, but also the foot. Additionally, the base element(s) may include one or more slits which ensure the flexibility of the stability element in the forefoot portion, as necessary, for an unhindered push-off phase. For the support of the longitudinal and/or lateral arch of the foot, the base element(s) may include an additional support element in the forefoot portion. The support element may extend from the side of the stability element. The stability element may also include at least one side element that extends upwardly from the side of the stability element over the edge of the footwear. This embodiment is particularly suited for use in sports with a high lateral strain on the foot.
These and other objects, along with advantages and features of the present invention herein disclosed, will become apparent through reference to the following description of embodiments of the invention, the accompanying drawings, and the claims.